[brianp-beme]

Paul is accurate in that he has the only known E90-1 blank back subject (Krause), because Krause is not seen in any other set but the E90-1.

I have removed E105 and E106 cards from the below list due to the points made. The below list shows the possible other sets (E90-1, E101 and E102) that these subjects are in besides the E92 sets.

Chase fielding: E101, E102
Crawford red: E101, E102
Davis sliding: E101
Dougherty: E90-1, E101, E102
Gibson back view: E101
Lajoie fielding: E101, E102
McGraw: E101
McLean: E90-1, E101
Miller fielding: E90-1, E101, E102
Schlei: E101
Seigle: E90-1, E101
Smith: E101, E102
Tinker batting: E101, E102
Wagner throwing: E90-1, E101, E102
Zimmerman: E101, E102

As you can see, besides all these cards being in the E92 sets, they are all also in the E101. With Paul's E90-1 Krause showing that it is possible for E90-1 cards (and thus other sets) to have blank backs, I think we can only narrow things down to the above list, unless there are some recognizable printing differences between sets of the same subject.

Just like tobacco cards and blank backs being seen in all the major sets, my guess is that E90-1, E101 and E102 could possibly be the source of these blank backs.

Everybody have fun trying to figure all this blank back action out!

Brian